#include "TcpConnection.h"

static EventLoop* CheckLoopNotNull(EventLoop *loop)
{
    if (loop == nullptr)
    {
        LOG_FATAL("%s:%s:%d TcpConnection Loop is null! \n", __FILE__, __FUNCTION__, __LINE__);
    }
    return loop;
}

TcpConnection::TcpConnection(EventLoop* loop, 
                const std::string& nameArg, 
                int sockfd,
                const InetAddress& localAddr,
                const InetAddress& peerAddr)
    : loop_(CheckLoopNotNull(loop))
    , name_(nameArg)
    , state_(kConnecting)
    , reading_(true)
    , socket_(new Socket(sockfd))
    , channel_(new Channel(loop, sockfd))
    , localAddr_(localAddr)
    , peerAddr_(peerAddr)
    , highWaterMark_(64*1024*1024) // 64M
{
    // 下面给Channel设置相应的回调函数，Poller给Channel通知
    // 感兴趣的事件发生了，Channel会回调相应的操作函数
    channel_->setReadCallback(std::bind(&TcpConnection::handleRead, this, std::placeholders::_1));
    channel_->setWriteCallback(std::bind(&TcpConnection::handleWrite, this));
    channel_->setCloseCallback(std::bind(&TcpConnection::handleClose, this));
    channel_->setErrorCallback(std::bind(&TcpConnection::handleError, this));

    LOG_INFO("TcpConnection::ctor[%s] at fd=%d\n", name_.c_str(), sockfd);
    socket_->setKeepAlive(true);
}


TcpConnection::~TcpConnection()
{
    LOG_INFO("TcpConnection::dtor[%s] at fd=%d state=%d\n", name_.c_str(), channel_->fd(), (int)state_);
}

void TcpConnection::send(const std::string &buf)
{
    if (state_ == kConnected)
    {
        if (loop_->isInLoopThread())
        {
            sendInLoop(buf.c_str(), buf.size());
        }
        else
        {
            loop_->runInLoop(std::bind(&TcpConnection::sendInLoop, this, buf.c_str(), buf.size()));
        }
    }
}

/**
 * 发送数据：应用写的快而内核发送数据慢， 则需要把待发送数据写入缓冲区， 而且设置了水位回调
 */ 
void TcpConnection::sendInLoop(const void* data, size_t len)
{
    ssize_t nwrote = 0;
    size_t remaining = len;
    bool faultError = false;

    // 之前调用过该Connection的shutdown，就不能再进行发送了
    if (state_ == kDisconnected)
    {
        LOG_ERROR("disconnected, give up writing\n");
        return;
    }

    // 表示channel_第一次开始写数据，而且缓冲区没有待发送数据
    if (!channel_->isWriting() && outputBuffer_.readableBytes() == 0)
    {
        nwrote = ::write(channel_->fd(), data, len);
        if (nwrote >= 0)
        {
            remaining = len - nwrote;
            if (remaining == 0 && writeCompleteCallback_)
            {
                // 既然在这里数据全部发送完成，就不用再给channel设置epollout事件了
                loop_->queueInLoop(std::bind(writeCompleteCallback_, shared_from_this()));
            }
        }
        else
        {
            nwrote = 0;
            if (errno != EWOULDBLOCK)
            {
                LOG_ERROR("TcpConnection::sendInLoop");
                if (errno == EPIPE || errno == ECONNRESET)
                {
                    faultError = true;
                }
            }
        }
    }

    // 说明当前这一次write，并没有把数据全部发送出去，剩余的数据需要保存到缓冲区当中，然后给channel
    // 注册epollout事件，poller发现tcp的发送缓冲区有空间，会通知相应的sock-channel，调用writeCallback_回调方法
    // 也就是调用TcpConnection::handleWrite方法，把发送缓冲区中的数据全部发送完成
    if (!faultError && remaining > 0) 
    {
        // 目前发送缓冲区剩余的待发送数据的长度
        size_t oldLen = outputBuffer_.readableBytes();
        if (oldLen + remaining >= highWaterMark_
            && oldLen < highWaterMark_
            && highWaterMarkCallback_)
        {
            loop_->queueInLoop(std::bind(highWaterMarkCallback_, shared_from_this(), oldLen+remaining));
        }
        outputBuffer_.append((char*)data + nwrote, remaining);
        if (!channel_->isWriting())
        {
            // 这里一定要注册Channel的写事件，否则Poller不会给Channel通知EPOLLOUT
            channel_->enableWriting(); 
        }
    }
}

// 关闭连接
void TcpConnection::shutdown()
{
    if (state_ == kConnected)
    {
        setState(kDisconnecting);
        loop_->runInLoop(std::bind(&TcpConnection::shutdownInLoop, this));
    }
}

void TcpConnection::shutdownInLoop()
{
    // 说明outputBuffer中的数据已经全部发送完成
    if (!channel_->isWriting()) 
    {
        socket_->shutdownWrite(); // 关闭写端
    }
}

// 建立连接
void TcpConnection::connectEstablished()
{
    setState(kConnected);
    channel_->tie(shared_from_this());
    // 向Poller注册Channel的EPOLLIN事件
    channel_->enableReading(); 
    // 新连接建立，执行回调
    connectionCallback_(shared_from_this());
}

// 销毁连接
void TcpConnection::connectDestroyed()
{
    if (state_ == kConnected)
    {
        setState(kDisconnected);
        // 将Channel的所有感兴趣的事件从Poller中删除掉
        channel_->disableAll(); 
        connectionCallback_(shared_from_this());
    }
    // 把Channel从Poller中删除掉
    channel_->remove(); 
}

void TcpConnection::handleRead(Timestamp receiveTime)
{
    int savedErrno = 0;
    ssize_t n = inputBuffer_.readFd(channel_->fd(), &savedErrno);
    if (n > 0)
    {
        // 已建立连接的用户的可读事件发生了，调用用户传入的回调操作onMessage
        messageCallback_(shared_from_this(), &inputBuffer_, receiveTime);
    }
    else if (n == 0)
    {
        handleClose();
    }
    else
    {
        errno = savedErrno;
        LOG_ERROR("TcpConnection::handleRead");
        handleError();
    }
}

void TcpConnection::handleWrite()
{
    if (channel_->isWriting())
    {
        int savedErrno = 0;
        ssize_t n = outputBuffer_.writeFd(channel_->fd(), &savedErrno);
        if (n > 0)
        {
            outputBuffer_.retrieve(n);
            if (outputBuffer_.readableBytes() == 0)
            {
                channel_->disableWriting();
                if (writeCompleteCallback_)
                {
                    // 唤醒loop_对应的线程执行回调
                    loop_->queueInLoop(std::bind(writeCompleteCallback_, shared_from_this()));
                }
                if (state_ == kDisconnecting) 
                {
                    shutdownInLoop();
                }
            }
        }
        else
        {
            LOG_ERROR("TcpConnection::handleWrite");
        }
    }
    else
    {
        LOG_ERROR("TcpConnection fd=%d is down, no more writing\n", channel_->fd());
    }
}

// Poller => Channel::closeCallback => TcpConnection::handleClose
void TcpConnection::handleClose()
{
    LOG_INFO("TcpConnection::handleClose fd=%d state=%d \n", channel_->fd(), (int)state_);
    setState(kDisconnected);
    channel_->disableAll();

    TcpConnectionPtr connPtr(shared_from_this());
    connectionCallback_(connPtr); // 执行连接关闭的回调
    closeCallback_(connPtr); // 关闭连接的回调  执行的是TcpServer::removeConnection回调方法
}

void TcpConnection::handleError()
{
    int optval;
    socklen_t optlen = sizeof optval;
    int err = 0;
    if (::getsockopt(channel_->fd(), SOL_SOCKET, SO_ERROR, &optval, &optlen) < 0)
    {
        err = errno;
    }
    else
    {
        err = optval;
    }
    LOG_ERROR("TcpConnection::handleError name:%s - SO_ERROR:%d \n", name_.c_str(), err);
}